BoilerFaultCodesYour boiler has detected that a temperature sensor has stuck on a single reading, meaning it cannot accurately tell how hot the water is to safely heat your home.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow NTC error – flow temperature sensor signal constant value
What causes this fault?
This fault occurs when the boiler's internal computer notices that the temperature reading from the flow sensor isn't changing, even though the burner is firing. The most common reason is that the sensor has physically failed or 'seized' internally, but it can also be caused by a loose connection or damaged wiring that prevents the sensor from sending updated data.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like F.71 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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